However, this recommended HCQ dosage regimen was based only on the ratio of free lung trough concentration to in vitro EC50 values (the EC50 of HCQ for SARS-CoV-2 ranged between 0.72 and 17.31µM) and did not consider the tendency of HCQ to accumulate within acidic cellular organelles like endosomes, lysosomes, and Golgi apparatus [69].